The present invention relates to systems and methods for calibrating sensory stimuli. More particularly, the present invention relates to systems and methods that calibrate sensory stimuli to ensure that the beginning and the duration of a range of response time is substantially consistent across computer platforms.
Diagnostic/training computer software typically present sensory stimuli, such as sound and/or tone, visual stimuli, touch stimuli, or the like across a user interface with the intention of eliciting a response from the user. The diagnostic and training software, for example, may be implemented in an educational program that is designed to build language skills in children. Development of language skills is especially important in those children who lack the necessary skills to make reliable distinctions among speech sounds and therefore suffer from poor language comprehension and/or speech production problems.
In order to make the diagnostic and/or training process a positive experience for the user, the diagnostic/training software is often presented to the user in the form of a computer game. In the computer game, the user may be rewarded or penalized points depending on the user's response and reaction time to sound and/or tone stimuli. By way of example, one such computer diagnostic/training software is Old McDonald's Flying Farm (OMDFF), commercially available from Scientific Learning Corporation of Berkeley, Calif. Although the disclosure herein focuses on sound and/or tonal stimuli to simplify the discussion, it should be borne in mind that the issues presented herein and the techniques proposed by the present invention are also applicable when other forms of sensory stimuli are employed.
By way of example, the sound and/or tone stimuli may include a string of tones and may be stored in a memory storage device, e.g., a CD ROM or a magnetic media. Such stimuli are commonly referred to in the art as "STIMs". FIG. 1 shows a representative STIM 10 and a timeline associated with STIM 10. STIM 10 includes several dummy tones 20 followed by a target tone 26. In response to STIM 10, a user attempts to discern between dummy tones 20 and target tone 26 to identify a speech pattern associated with STIM 10. By way of example, dummy tones 20 may denote a "BA" sound and target tone 26 may denote a "DA" sound, and the user attempts to distinguish between the "BA" sound and the "DA" sound by activating a user input device (e.g., clicking on a mouse) when the user believes that the "DA" sound has been played. The user's response to the STIM presented and the user's reaction time to target tone 26 provides insight into the user's ability to recognize language and speech patterns.
For simplicity's sake, the remainder of the disclosure will focus on the mouse as the user input device employed by the user to signal his response. It should be noted, however, that the techniques disclosed herein are also applicable when other types of user input devices are employed, e.g., keyboards, microphones, virtual reality input devices, or other transducers.
Before the timeline of STIM 10 begins at time T equals zero, there exists a seek time 12, during which the computer or a processor employed to produce the stimuli seeks the sound file containing STIM 10 that is stored on the memory storage device. Once the sound file is found, the timeline of STIM 10 begins at time T equals zero, as shown in FIG. 1. As the time progresses after time T equals zero, a dead time 14, which may last about 100 ms, precedes the actual playback of STIM 10. During dead time 14, no sound is typically played by the computer or processor.
The first dummy tone 20 is heard after a period of time 18 known as inter stimulus interval (ISI) elapses. Each of dummy tones 20 lasts for a period of time 16 and is separated from one another by an ISI 18. In other words, the length of an ISI spans from the end of a previous dummy tone to the beginning of a subsequent dummy tone. According to FIG. 1, a string of dummy tones 20 and ISIs 18 are presented to the user. After the last dummy tone 20 is played and the last ISI 18 elapses, however, target tone 26 is presented.
A lock out time 22 typically follows the last ISI 18. During this period of time, the user is typically locked out from registering a response. The lock out time accounts for a period of time required by an average human being to register a viable cognitive input, i.e. hear, recognize and then respond to the target tone. After the lock out time has expired, the software is ready to receive the user's response to the target tone for a period of time that is referred to as the "hit window."
It is important to note that in order to respond to STIM 10 correctly, the user should respond within the duration of hit window 24. If the user responds before hit window 24 or after hit window 24 then the user's response is deemed an incorrect response. The time period of hit window 24 begins at a starting time of the hit window and concludes at an ending time of the hit window, and the time period spanning between the starting and ending of the hit window typically equals a dummy letter. The dummy letter is defined as the sum of duration of a dummy tone (shown by reference number 16 in FIG. 1) and an ISI 18.
Measuring from the point when time equals zero, the starting time of the hit window is defined as the sum of the dead time 14, the lockout time 22 plus the product of the number of dummy tones 20 in the STIM and the duration of a dummy letter. The ending time of the hit window may be calculated as the sum of dead time 14, lockout time 22, the product of the number of dummy tones 20 in the STIM and the duration of a dummy letter, plus the duration of hit window 24.
Ideally, the duration of the hit window as well as its beginning and/or ending should stay constant relative to the stimuli irrespective of the computer employed to administer the computer-implemented diagnostic/training regime. Unfortunately, when the computer that is employed to administer the computer-implemented diagnostic/training regime is implemented differently from the computer that is employed to author the diagnostic/training software, the duration of the hit window changes and/or the hit window undesirably shifts or drifts from its relative preset position in the sound file. This can happen if the administering computer supports a different platform, has a different hardware configuration (e.g., different processor, bus, memory capacity, I/O subsystem, or the like), or is simply implemented with a different operating system/browser than that associated with the authoring computer. As an example, although the target tone may be presented to the user at substantially the same time when different computers are employed to run the software, the lock out time that follows the target tone may have different durations.
By way of example, when the software-authoring computer is an Apple MacIntosh.RTM. BY Apple Computer Inc. of Cupertino, Calif., and the software is subsequently executed on an Intel-based computer (also known as an IBM-compatible computer), it has been observed that typically the lock out time on the IBM-compatible computer increases relative to the lockout time initially set on the Apple MacIntosh.RTM.. Thus, the hit window is presented to the user later in time when using an IBM-compatible computer than if an Apple computer is used.
Because of the shift or change in duration in the hit window, it is difficult to analyze users' responses in a meaningful way when different administering computers are employed. This is because a response which is timely and correct on one computer may be deemed untimely and incorrect in another computer, although neither the underlying diagnostic/training software nor the user's response has changed.
What is therefore needed is a process and a system that can quickly and accurately determine the location of the hit window relative to the stimulus and its duration when a given computer is employed to administer the diagnostic/training software.